kern.securelevel: 0 -> 1 creating runtime link editor directory cache. preserving editor files. starting network daemons: sshd. starting local daemons:. Thu Sep 26 03:28:55 PDT 2019 OpenBSD/amd64 (ci-openbsd-multicore-0.c.syzkaller.internal) (tty00) Warning: Permanently added '10.128.10.1' (ECDSA) to the list of known hosts. 2019/09/26 03:29:05 parsed 1 programs 2019/09/26 03:29:12 executed programs: 0 2019/09/26 03:29:17 executed programs: 121 2019/09/26 03:29:22 executed programs: 249 login: panic: tcp_output: template len != hdrlen - optlen Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND 62236 57317 0 0x2 0 0K syz-executor.0 *295219 57335 0 0x12 0 1 sshd db_enter() at db_enter+0x18 panic() at panic+0x15c tcp_output(ffff800000a7a100) at tcp_output+0x2c28 tcp_usrreq(fffffd806e975c08,9,fffffd806d6c3400,0,0,ffff800020ac1b38) at tcp_usrreq+0xa45 sosend(fffffd806e975c08,0,ffff800020aeb408,0,0,80) at sosend+0x645 dofilewritev(ffff800020ac1b38,4,ffff800020aeb408,0,ffff800020aeb4f0) at dofilewritev+0x1b7 sys_write(ffff800020ac1b38,ffff800020aeb4a0,ffff800020aeb4f0) at sys_write+0x83 syscall(ffff800020aeb570) at syscall+0x4a4 Xsyscall(6,4,8e421f1616b,4,4,8e6c4eb1080) at Xsyscall+0x128 end of kernel end trace frame: 0x7f7ffffc4cb0, count: 6 https://www.openbsd.org/ddb.html describes the minimum info required in bug reports. Insufficient info makes it difficult to find and fix bugs. ddb{1}> ddb{1}>